Advanced Materials Research Vols. 255-260

Abstract: The concept of equivalent number of uniform stress cycles, is essential for assessment of soil liquefaction potential. In this regard, various procedures are used to convert random acceleration time history to uniform cycles having amplitude of 0.65 of peak acceleration. Equivalent number of cycles (N_eq) defines equivalent energy generated by harmonic loading as that imposed by irregular motion during an earthquake. N_eq is assumed to be a function of earthquake magnitude. Over the past years, in accordance with development in methods of soil liquefaction evaluation, various methods have been proposed to determinate equivalent number of cycles. In particular, parameters like site to source distance (r), have been related directly to N_eq. In this study, more than 80 earthquake records have been investigated and their N_eqs are assessed using energy approach and nonlinear site response analysis. It is shown that equivalent number of cycles is related to earthquake magnitude (M), r and depth of originated signals. Unlike previous methods which result in scatter in output data, current approach has led to more uniform and consistent results for each earthquake.

Abstract: The propagation characteristics and laws of concrete sandwich with foam soft interlayer under contact explosion were studied by numerical simulation. Based on a reasonable choice of the constitutive model and physical parameters by numerical methods, the plane blast wave propagation features of the concrete structure are illustrated, including the stress wave propagation and attenuation, space-time evolution of damage and wave reflection and transmission at layered interfaces, and the total energy distribution in various medium layers. The structural failure and destruction of two-dimensional dynamic process was reproduced by numerical computation. Meanwhile, it is pointed out that the role of soft interlayer in concrete sandwich structure is mainly by its low wave impedance, the waveform of incident wave is changed and stress wavelength is pull wide, the radial diffusion of energy is enhanced and the amplitude of impulse and energy inputting the third layer is reduced, thus as a result the protective performance of overall concrete sandwich structure is improved.

Abstract: Through analysis of seismic collapse damages of buildings during Wenchuan and Yushu earthquakes, structural system method is proposed to expound the relationship between structural system and energy and to analyze their applications in the study of seismic collapse.

Abstract: In order to analysis the seismic resistance mechanism of Staff apartment block of Beichuan telecommunication bureau (a six-storey-high masonry building in Beichuan County, meizoseismal area of Wenchuan earthquake), which just suffered from a moderate damage in the earthquake, ambient vibration survey and numerical simulation of structural earthquake response are carried out. Based on the ambient vibration survey, the natural frequencies of the building are acquired after Wenchuan earthquake. The first natural frequency in transverse and longitudinal is 3.45Hz and 3.65Hz, respectively, and the torsion frequency is 4.05Hz. The second natural frequency of the building in transverse is 7.55Hz, and that in longitudinal is not tested out. With Abaqus software, the earthquake response is computed out by inputting Wolong earthquake wave recorded in Wenchuan earthquake. The results of numerical simulation illustrate that the maximum acceleration amplification factor of the top floor in transverse and longitudinal is 5.28 and 6.68 severally. The maximum inter-story drift in transverse and longitudinal is 1/359 and 1/274 respectively, which are all exceed the limit of inter-story drift of masonry structure.

Abstract: Application of continuum structural topology optimization methods to the layout design of bracing systems for multistory steel frame buildings under earthquake loads is explored in this work. A weighted average strain energy sensitivity of element is formulated to be served as the element removal criterion in the optimization process, and then an ESO-based continuum structural topology optimization method for the layout design of multistory steel frame bracing systems subjected to earthquake-induced ground motions is presented. In each iterative design, an approximate reanalysis technique named CA method is adopted to reduce the computational effort. Finally, a design example is given to demonstrate the effectiveness of the presented optimization method for the optimal layout design of steel frame bracing systems under earthquake loads.

Abstract: This paper based on the analysis of typical industrial plants equipment foundation damage caused by 5.12 wenchuan earthquake to conduct preliminary research on earthquake resistance & seismic isolation ability for mass concrete equipment foundation and finally offers several constructive suggestions for rehabilitation and reconstruction.

Abstract: Based on the investigation of damage situations of some reinforced concrete industrial factory buildings in Chengdu affected by Wenchuan Earthquake, and the typical seismic damage analysis of the roof, skylight truss, columns, column bracing and building envelope, this article puts forward several repair and reinforcement measures and methods for reference.

Abstract: This article investigated the damage conditions of cereals infrastructures in city of Mianyang, Sichuan province, after the ‘5.12’ Wenchuan Earthquake. The guidelines of restoration and reconstruction program with cereals infrastructure were brought forward in this paper. Based on the analysis of local cereals production and consumption, as well as the prediction of social development in the future, this article proposed respectively the restoration and reconstruction projects those should be planned. Economic benefit and social benefit to be brought by these projects were also analyzed. This paper will provide some references to the recovery of other cities those also destroyed in the earthquake.

Abstract: This article compared the two supporting structure programs which were prepared for the foundation pit of Zhengzhou Exhibition Hotel, from the angle of cost, duration, and deformation conditions. The better one was selected for the project. Monitoring results of two important indicators with the security of supporting structure were analyzed, they were deep displacement in supporting structure and displacement of pile top. With the conditions of continuous excavation, this paper also concluded shifty discipline and tendency of the supporting structure, which could provide some references to similar projects.

Abstract: Because the repairing work of beam and floor after earthquake were great, and the cost were higher, the generalize application of eccentrically braced steel frame were limited. A new braced steel frame system was suggested, which was energy dissipating eccentrically brace. The experimental data of new and conventional D-type eccentrically braced steel frame system were achieved by two specimens under cyclic loading. Results indicated that the new system could put off yielding, reduce earthquake input energy and breakage of the link, reduce repairing load after earthquake, and have preferable ductility and enough lateral stiffness. The new braced steel frame system which had gained patent of invention in Chinese was practical and costly that it could be applied in present project.